Open-phase fault monitoring system

Abstract

The present disclosure relates to the technical field of electrical device state monitoring, and particularly discloses an open-phase fault monitoring system, in which a relay communication unit is configured with an MCU as a central control processing unit, and an external ADC realizes high-speed A/D conversion for a plurality of signals; a timing function is realized by a GNSS&RTC of the relay communication unit, a data interaction function is realized by a LORA module, and data is sent to a background industrial personal computer based on a designed sampling frequency. The system of the present disclosure has the advantages of small volume, high precision, low cost, easy installation and the like, and realizes real-time monitoring and accurate identification of a line open-phase fault of an auxiliary power supply system in a nuclear power plant.

The invention claimed is: 
     
         1 . An open-phase fault monitoring system, comprising a current monitoring unit, a relay communication unit, an energy extraction unit and a data processing unit, wherein:
 the current monitoring unit is configured to monitor multipath current signals, and comprises a cable current monitoring unit and a ground current monitoring unit, wherein the cable current monitoring unit is configured to monitor current flowing through a transformer cable, and the ground current monitoring unit is configured to monitor current flowing through a reverse current ground wire;   each of the cable current monitoring unit and the ground current monitoring unit is an ring shape and is enclosed by two ferrite rings, where a center hole passes through a conductor to be measured and a magnetic ring air gap is machined on one of the ferrite rings to arrange a current monitoring unit circuit, wherein one terminal of each of the two ferrite rings is connected by a rotation shaft, and the other terminal thereof is provided with a connecting line interface where a connecting line is inserted to connect the current monitoring unit with the relay communication unit; the cable current monitoring unit and the ground current monitoring unit have a same circuit structure, both comprising two magnetic field sensing chips with tunnel junction magneto-resistive type, and the two magnetic field sensing chips with tunnel junction magneto-resistive type are correspondingly connect to two instrument amplifier circuits and two electric energy management modules of the current monitoring unit;   a hardware part of the relay communication unit comprises a body, an antenna, a connecting line interface C, a battery compartment, a system restart key and a debugging interface; a circuit part of the relay communication unit is disposed on a printed circuit board, and comprises an MCU, a LORA module, an ADC a FLASH&WD, a GNSS&RTC module, a power management module of the relay communication unit and corresponding resistor-capacitor elements connected to the power management module;   the antenna is disposed at the top of the body and connected to the LORA module and the GNSS&RTC module in the body of the relay communication unit; the LORA module enhances a signal via the antenna, and wirelessly sends data to the data processing unit for data processing; the GNSS&RTC module obtains time data from a satellite via the antenna to realize a data transceiving function of the relay communication unit; the connecting line interfaces C is disposed at the bottom of the body for a wired connection between the relay communication unit and the energy extraction unit and the current monitoring unit, and the connecting line interface C is connected to the printed circuit board and the power management module of the relay communication unit inside the body; and the battery compartment is disposed on a lateral side of the body, with a battery placed therein, and the battery is connected to the printed circuit board inside the body; the system restart key and the debugging interface are disposed on a lateral side of the body, the relay communication unit is refreshed by clicking the system restart key, and the relay communication unit is connected to a computer by the debugging interface, so as to modify and debug a program of the relay communication unit;   the MCU of the relay communication unit is used as a central control processing unit and connected to ADC peripheral, the ADC converts the transmitted analog signal into a digital signal, and multipath analog signals is obtained in a short time; the FLASH&WD stores the data obtained and converted by the ADC, and the data is written into the FLASH&WD after being processed by the MCU, so that the past data is queried when the open-phase fault monitoring system is failed;   the LORA module is connected to the MCU on the printed circuit board to realize a function of data wireless communication, and a working condition of the LORA module is controlled by the MCU to realize a continuous or intermittent data transmission to an industrial personal computer;   the GNSS&RTC realizes a time calibration by a connection with the MCU to provide accurate moment signals, and calibrates a system clock continuously or intermittently;   the energy extraction unit comprises two independent groups of magnetic ring for obtaining electrical energy based on induction principle, corresponding connecting circuits and a connecting line interface D; the inductive electromagnetic ring is wound with a coil, an outlet terminal of the coil is connected to an input terminal of the printed circuit board, and a rectifier bridge composed of capacitors is arranged on the printed circuit board; the rectifier bridge comprises two input terminals connected to two terminals of the coil respectively and an output terminal connected to an input terminal of a voltage regulator chip, and an output terminal of the voltage regulator chip outputs via the connecting line interface D; and the energy extraction unit obtains electric energy and supplies power to the current monitoring unit and the relay communication unit; and   the data processing unit wirelessly receives information sent by the relay communication unit to perform a data analysis, and comprises the industrial personal computer, a relay and a LORA receiving device; the industrial personal computer is in wired connection the relay by a USB serial port, and directly connected to the LORA receiving device by a USB serial port; the industrial personal computer receives current data sent by the LORA module in the relay communication unit by the LORA receiving device, and the current data is directly read by the industrial personal computer by the USB serial port with a serial communication mode; the industrial personal computer judges phase opening based on the current data and controls the output of the relay.   
     
     
         2 . The open-phase fault monitoring system according to  claim 1 , wherein:
 the magnetic field sensing chip with tunnel junction magneto-resistive type is configured to monitor and convert a magnetic field intensity of the conductor to be measured into an analog differential voltage, wherein an output terminal of the magnetic field sensing chip with magneto-resistive type is connected to the instrument amplifier circuit; the instrument amplifier circuit is implemented by combining an instrument amplification chip with a resistor-capacitor element to amplify the analog differential voltage and output an analog voltage signal; and   the electric energy management module of the current monitoring unit is composed of a voltage regulator chip, and the voltage regulator chip is connected to the magnetic field sensing chip with magneto-resistive type and the instrument amplifier circuit, respectively, so as to provide a power supply voltage for the magnetic field sensing chip with magneto-resistive type and the instrument amplifier circuit, and provide a reference voltage for the instrument amplifier circuit.   
     
     
         3 . The open-phase fault monitoring system according to  claim 1 , wherein the connecting line interface C is in wired connection with the connecting line interface D of the energy extraction unit to supply power for the relay communication unit, and an output terminal of the power management module of the relay communication unit is in wired connection with the connecting line interface C inside the body. 
     
     
         4 . The open-phase fault monitoring system according to  claim 3 , wherein the connecting line interface C is connected to connecting line interfaces A and B of the current monitoring unit to supply power for the current monitoring unit and realize an information transmission. 
     
     
         5 . The open-phase fault monitoring system according to  claim 4 , wherein:
 the output terminal of the power management module of the relay communication unit is in wired connection with the connecting line interface C, and an input terminal of the power management module of the current monitoring unit is in wired connection with the connecting line interfaces A and B; and   an analog signal output terminal of the current monitoring unit is connected to the connecting line interfaces A and B of the current monitoring unit by cables, an ADC input terminal of the relay communication unit is connected to the connecting line interface C by cables, and the connecting line interfaces A and B of the current monitoring unit are externally in wired connection with the connecting line interface C of the relay communication unit.   
     
     
         6 . The open-phase fault monitoring system according to  claim 1 , wherein the wired connection between the relay communication unit and the current monitoring unit is configured with multi-core wires, so that a current obtainment signal output by the current monitoring unit is transmitted to the relay communication unit, and energy output by the energy management module of the relay communication unit is transmitted to a plurality of the current monitoring units. 
     
     
         7 . The open-phase fault monitoring system according to  claim 1 , wherein the hardware part of the relay communication unit further comprises thermal fins ( 4 - 2 ) uniformly distributed outside the body to reduce accumulated heat generated when the relay communication unit works. 
     
     
         8 . The open-phase fault monitoring system according to  claim 1 , wherein if intermittent timing is configured with, the MCU uses its own clock or a peripheral crystal oscillator clock to count time when a timing module of the GNSS&RTC is closed, so as to achieve a time measurement. 
     
     
         9 . The open-phase fault monitoring system according to  claim 1 , wherein:
 when the data processing unit starts to work, firstly, the LORA receiving device monitors whether there is any new data accessed by the LORA module of the relay communication unit; if so, a data format is checked, stored and written into a database, and if there are an outlier, the outlier is cleaned in corresponding formats; next, it is judged whether there is any device abnormality or phase opening;   when any one of the following situations occurs, it is determined that there is a device abnormality:   a) communication abnormality judgment: if one current monitoring unit does not receive data for five consecutive data time points, it is determined that the communication is abnormal and a background reports an alarm ‘the relay communication unit is abnormal’;   b) abnormality judgment of one current monitoring unit: when the data of one current monitoring unit is 0±0.05 or a difference with other two current monitoring units is much greater than one time, it is determined that the one current monitoring unit is abnormal; and   after the device abnormality is eliminated, the data of each current monitoring unit is continuously monitored, and the data incoming from the one current monitoring unit appearing abnormal for two consecutive times is judged; if there is no same abnormality, it is determined that an abnormal event is eliminated.   
     
     
         10 . The open-phase fault monitoring system according to  claim 9 , wherein if current monitoring data received by the data processing unit meets the following two conditions at the same time, and a same abnormality occurs for two consecutive times, it is determined that an open-phase fault has occurred:
 a) open-phase judgment based on a threshold: when phase opening occurs, generally, currents of a ground wire and a core wire of a wire of one phase are dropped and disappeared, and when currents of the ground wire and the core wire both drop to near zero, while currents of other sensors still exist, it is determined that there is an open-phase event;   b) open-phase judgment based on zero-sequence current: under normal working conditions, there is no zero-sequence current in either of the core wire and the ground wire, and when calculated zero-sequence currents in both the core wire and the ground wire exceed a threshold, it is determined that there is an open-phase event;   the current monitoring data received by the data processing unit is continuously monitored after the open-phase fault is eliminated, and when a same abnormality does not appear for two consecutive times, it is determined that an abnormal event is eliminated.   
     
     
         11 . The open-phase fault monitoring system according to  claim 2 , wherein:
 when the data processing unit starts to work, firstly, the LORA receiving device monitors whether there is any new data accessed by the LORA module of the relay communication unit; if so, a data format is checked, stored and written into a database, and if there are an outlier, the outlier is cleaned in corresponding formats; next, it is judged whether there is any device abnormality or phase opening,   when any one of the following situations occurs, it is determined that there is a device abnormality:   a) communication abnormality judgment: if one current monitoring unit does not receive data for five consecutive data time points, it is determined that the communication is abnormal and a background reports an alarm ‘the relay communication unit is abnormal’;   b) abnormality judgment of one current monitoring unit: when the data of one current monitoring unit is 0±0.05 or a difference with other two current monitoring units is much greater than one time, it is determined that the one current monitoring unit is abnormal; and   after the device abnormality is eliminated, the data of each current monitoring unit is continuously monitored, and the data incoming from the one current monitoring unit appearing abnormal for two consecutive times is judged; if there is no same abnormality, it is determined that an abnormal event is eliminated.   
     
     
         12 . The open-phase fault monitoring system according to  claim 3 , wherein:
 when the data processing unit starts to work, firstly, the LORA receiving device monitors whether there is any new data accessed by the LORA module of the relay communication unit; if so, a data format is checked, stored and written into a database, and if there are an outlier, the outlier is cleaned in corresponding formats; next, it is judged whether there is any device abnormality or phase opening;   when any one of the following situations occurs, it is determined that there is a device abnormality:   a) communication abnormality judgment: if one current monitoring unit does not receive data for five consecutive data time points, it is determined that the communication is abnormal and a background reports an alarm ‘the relay communication unit is abnormal’;   b) abnormality judgment of one current monitoring unit: when the data of one current monitoring unit is 0±0.05 or a difference with other two current monitoring units is much greater than one time, it is determined that the one current monitoring unit is abnormal; and   after the device abnormality is eliminated, the data of each current monitoring unit is continuously monitored, and the data incoming from the one current monitoring unit appearing abnormal for two consecutive times is judged; if there is no same abnormality, it is determined that an abnormal event is eliminated.   
     
     
         13 . The open-phase fault monitoring system according to  claim 4 , wherein:
 when the data processing unit starts to work, firstly, the LORA receiving device monitors whether there is any new data accessed by the LORA module of the relay communication unit, if so, a data format is checked, stored and written into a database, and if there are an outlier, the outlier is cleaned in corresponding formats; next, it is judged whether there is any device abnormality or phase opening;   when any one of the following situations occurs, it is determined that there is a device abnormality:   a) communication abnormality judgment: if one current monitoring unit does not receive data for five consecutive data time points, it is determined that the communication is abnormal and a background reports an alarm ‘the relay communication unit is abnormal’;   b) abnormality judgment of one current monitoring unit: when the data of one current monitoring unit is 0±0.05 or a difference with other two current monitoring units is much greater than one time, it is determined that the one current monitoring unit is abnormal; and   after the device abnormality is eliminated, the data of each current monitoring unit is continuously monitored, and the data incoming from the one current monitoring unit appearing abnormal for two consecutive times is judged; if there is no same abnormality, it is determined that an abnormal event is eliminated.   
     
     
         14 . The open-phase fault monitoring system according to  claim 5 , wherein:
 when the data processing unit starts to work, firstly, the LORA receiving device monitors whether there is any new data accessed by the LORA module of the relay communication unit; if so, a data format is checked, stored and written into a database, and if there are an outlier, the outlier is cleaned in corresponding formats; next, it is judged whether there is any device abnormality or phase opening;   when any one of the following situations occurs, it is determined that there is a device abnormality:   a) communication abnormality judgment: if one current monitoring unit does not receive data for five consecutive data time points, it is determined that the communication is abnormal and a background reports an alarm ‘the relay communication unit is abnormal’;   b) abnormality judgment of one current monitoring unit: when the data of one current monitoring unit is 0±0.05 or a difference with other two current monitoring units is much greater than one time, it is determined that the one current monitoring unit is abnormal; and   after the device abnormality is eliminated, the data of each current monitoring unit is continuously monitored, and the data incoming from the one current monitoring unit appearing abnormal for two consecutive times is judged; if there is no same abnormality, it is determined that an abnormal event is eliminated.   
     
     
         15 . The open-phase fault monitoring system according to  claim 6 , wherein:
 when the data processing unit starts to work, firstly, the LORA receiving device monitors whether there is any new data accessed by the LORA module of the relay communication unit; if so, a data format is checked, stored and written into a database, and if there are an outlier, the outlier is cleaned in corresponding formats; next, it is judged whether there is any device abnormality or phase opening;   when any one of the following situations occurs, it is determined that there is a device abnormality:   a) communication abnormality judgment: if one current monitoring unit does not receive data for five consecutive data time points, it is determined that the communication is abnormal and a background reports an alarm ‘the relay communication unit is abnormal’;   b) abnormality judgment of one current monitoring unit: when the data of one current monitoring unit is 0±0.05 or a difference with other two current monitoring units is much greater than one time, it is determined that the one current monitoring unit is abnormal; and   after the device abnormality is eliminated, the data of each current monitoring unit is continuously monitored, and the data incoming from the one current monitoring unit appearing abnormal for two consecutive times is judged; if there is no same abnormality, it is determined that an abnormal event is eliminated.   
     
     
         16 . The open-phase fault monitoring system according to  claim 7 , wherein:
 when the data processing unit starts to work, firstly, the LORA receiving device monitors whether there is any new data accessed by the LORA module of the relay communication unit; if so, a data format is checked, stored and written into a database, and if there are an outlier, the outlier is cleaned in corresponding formats, next, it is judged whether there is any device abnormality or phase opening;   when any one of the following situations occurs, it is determined that there is a device abnormality:   a) communication abnormality judgment: if one current monitoring unit does not receive data for five consecutive data time points, it is determined that the communication is abnormal and a background reports an alarm ‘the relay communication unit is abnormal’;   b) abnormality judgment of one current monitoring unit: when the data of one current monitoring unit is 0±0.05 or a difference with other two current monitoring units is much greater than one time, it is determined that the one current monitoring unit is abnormal; and   after the device abnormality is eliminated, the data of each current monitoring unit is continuously monitored, and the data incoming from the one current monitoring unit appearing abnormal for two consecutive times is judged; if there is no same abnormality, it is determined that an abnormal event is eliminated.   
     
     
         17 . The open-phase fault monitoring system according to  claim 8 , wherein:
 when the data processing unit starts to work, firstly, the LORA receiving device monitors whether there is any new data accessed by the LORA module of the relay communication unit; if so, a data format is checked, stored and written into a database, and if there are an outlier, the outlier is cleaned in corresponding formats; next, it is judged whether there is any device abnormality or phase opening;   when any one of the following situations occurs, it is determined that there is a device abnormality:   a) communication abnormality judgment: if one current monitoring unit does not receive data for five consecutive data time points, it is determined that the communication is abnormal and a background reports an alarm ‘the relay communication unit is abnormal’;   b) abnormality judgment of one current monitoring unit: when the data of one current monitoring unit is 0±0.05 or a difference with other two current monitoring units is much greater than one time, it is determined that the one current monitoring unit is abnormal; and   after the device abnormality is eliminated, the data of each current monitoring unit is continuously monitored, and the data incoming from the one current monitoring unit appearing abnormal for two consecutive times is judged; if there is no same abnormality, it is determined that an abnormal event is eliminated.   
     
     
         18 . The open-phase fault monitoring system according to  claim 11 , wherein if current monitoring data received by the data processing unit meets the following two conditions at the same time, and a same abnormality occurs for two consecutive times, it is determined that an open-phase fault has occurred:
 a) open-phase judgment based on a threshold: when phase opening occurs, generally, currents of a ground wire and a core wire of a wire of one phase are dropped and disappeared, and when currents of the ground wire and the core wire both drop to near zero, while currents of other sensors still exist, it is determined that there is an open-phase event;   b) open-phase judgment based on zero-sequence current: under normal working conditions, there is no zero-sequence current in either of the core wire and the ground wire, and when calculated zero-sequence currents in both the core wire and the ground wire exceed a threshold, it is determined that there is an open-phase event;   the current monitoring data received by the data processing unit is continuously monitored after the open-phase fault is eliminated, and when a same abnormality does not appear for two consecutive times, it is determined that an abnormal event is eliminated.   
     
     
         19 . The open-phase fault monitoring system according to  claim 14 , wherein if current monitoring data received by the data processing unit meets the following two conditions at the same time, and a same abnormality occurs for two consecutive times, it is determined that an open-phase fault has occurred:
 a) open-phase judgment based on a threshold: when phase opening occurs, generally, currents of a ground wire and a core wire of a wire of one phase are dropped and disappeared, and when currents of the ground wire and the core wire both drop to near zero, while currents of other sensors still exist, it is determined that there is an open-phase event,   b) open-phase judgment based on zero-sequence current: under normal working conditions, there is no zero-sequence current in either of the core wire and the ground wire, and when calculated zero-sequence currents in both the core wire and the ground wire exceed a threshold, it is determined that there is an open-phase event;   the current monitoring data received by the data processing unit is continuously monitored after the open-phase fault is eliminated, and when a same abnormality does not appear for two consecutive times, it is determined that an abnormal event is eliminated.   
     
     
         20 . The open-phase fault monitoring system according to  claim 17 , wherein if current monitoring data received by the data processing unit meets the following two conditions at the same time, and a same abnormality occurs for two consecutive times, it is determined that an open-phase fault has occurred:
 a) open-phase judgment based on a threshold: when phase opening occurs, generally, currents of a ground wire and a core wire of a wire of one phase are dropped and disappeared, and when currents of the ground wire and the core wire both drop to near zero, while currents of other sensors still exist, it is determined that there is an open-phase event;   b) open-phase judgment based on zero-sequence current: under normal working conditions, there is no zero-sequence current in either of the core wire and the ground wire, and when calculated zero-sequence currents in both the core wire and the ground wire exceed a threshold, it is determined that there is an open-phase event;   the current monitoring data received by the data processing unit is continuously monitored after the open-phase fault is eliminated, and when a same abnormality does not appear for two consecutive times, it is determined that an abnormal event is eliminated.